Dyeing wooled sheepskins



Patented u 1, 1943 UNITED STATES PATENT OFFICE 2.336.321 DYEING WOOLED SHEEPSKINS John Burchill, Blackley, Manchester, England,

assignor to Imperial Chemical Industries Limited, a corporation of Great Britain No Drawing. Application June 14, 1941, Serial 1 Claim.

- method of applying oxidation dyestuffs, involving,

as it does, development of the colour by the step of oxidation on the fibre, tends to be lengthy, and involved. Then acid dyestuii's came also to be employed. These have the advantages of ease and simplicity of application and have extended the range of shades obtainable. Hitherto, however, it has only been possible to apply in this way a limited number of the acid dyestuffs available. Comparatively few acid dyestuffs, such as Citronine'Y (Colour Index No. 146), have sufflcient aflinity for the wool (or animal fibre) to be capable of dyeing at the relatively low temperature (40-50 C.) necessary to avoid injury to the skin. A considerable number, e. g., Lissamine Green V (Colour Index No. 735) and Naphthalene Black 123 (Colour Index No. 246) can be dyed on the wool after it has been chlorinated or at the higher temperatures (75-80 C.) permissible when the skin has been chrome-tanned. Some acid dyestuffs will not dye the wool suitably for commercial purposes even under these conditions.

Amongst these are for example, Lissamine Fast Yellow 2G (Colour Index No. 639) and A20 Geranine 2G (Colour Index No. 31). Moreover the processes of chlorination and chrome tanning are accompanied by many disadvantages. The former degrades the wool, impairs the handle and tends to make the resultant dyeing uneven. The latter is dlfllcult to control and liable to vary in its eflect on diiferent skins in a pack. Ftrthermore the dyeings hitherto obtainable in the above manner are apt to be uneven by reason of the preferential ailinity of the acid dyestufl. for the tip as compared with the root of the wool.

We have now found that by adding to the dyebath a small proportion of an assistant as hereinafter defined, not only can the dyeing be carried out without the previous chlorination or chrome-tanning referred to above but the resultant shade is of improved levelness and increased tinctorial strength. The last named aclvantageous improvements are also shown when the present process is applied in the case of those N0. 398,111. In Great Britain June 26, 1940 acid dyetuifs which dye wooled sheepskins without said pretreatments. Particularly is there found to be increased levelness attained as between tip and root. A further advantage'oi this invention is that 'itpermits the use of many acid dyestuffs hitherto inapplicable for the present purpose.

Accordingly the present invention relates to a process for dyeing wooled sheepskins, lambskins and the softer furs by means of acid dyestuffs,

comprising adding to the dyebath an assistant,

as hereinbelow defined.

As assistant in the dyebath thereis used according to the present invention a condensation product derivable from higher fatty or cycloaliphatic acids of not less than 8 carbon atoms, and an excess of glycerol under such conditions as to give an ester of polyglycerol (see British specification No. 450,868) mixed with 5m 25% of its weight of a quaternary ammonium salt, derived from an alkyl halide containing not less than 6 carbon atoms and a tertiary amine the nitrogen atom of which is part of a heterocyclic nucleus (see British specification 379,396).

For example there may be used; as assistant polyglyceryl ricinoleate containing a small proportion of cetyl pyridinium bromide. Polyglyceryl ricinoleate may be made by heating castor oil (30 parts) with glycerol (150 parts) in the presence of soap (5 parts) at 280 C. for 5 hours under steam jacketed reflux, and dissolving the product in twice its weight of water. Cetyl pyridinium bromide may be made by heating cetyl bromide (31 parts) with pyridine (8 parts) at C.

By the term acid dyestufl's we mean to include also those water-soluble dyestuffs which contain an.alkyl-su1phato grouping alkylene-O -SOz-OH- (cf. British specification No. 237,739), as, for example, the dyestui! obtained by coupling diazotised p-nitroaniline with N-ethyl-N-sulphatoethylaniline. The expression the softer furs" is intended to designate for the purposes of this invention such materials as moleskins and allied furs.

By applying acid dyestuffs in the dyeing of wooled sheepskins, lambskins and the softer furs in accordance with the present invention there are obtained shades of excellent levelness and good fastness to rubbing, light and washing.

The following examples in which the parts are by weight illustrate but do not limit the invention.

Example 1 2 parts of Lissamine Fast Yellow 2G (Colour Index 639) are dissolved together with an assistant consisting of 3.2 parts of polyglyceryl ricinoleate and 0.2 part of cetyl pyridinium bromide, in 2000 parts of water. This solution constitutes the dyebath.

100 parts dry weight of alum-vegetable-tanned long-haired Lincoln wooled sheepskins are immersed in the above solution at 45 C. After 25 minutes 2 parts of 30% acetic acid are added and dyeing continued for 20 minutes longer. The skins are then removed from the dyebath,

-Well rinsed in water at. 30-35 C., drained and at 45 C. After dyeing for minutes 1 parts of 30% acetic acid are added to the dyebath. After a further 15 minutes the lambskins are removed, well rinsed in water at 30-35 C.,

drained and dried at a temperature not exceed-- ing 45 C.

The skins are dyed a. bright green shade of very good levelness, and good fastness properties.

to rubbing,' I

Example 3 A dyebath is made by dissolving in- 500 parts of water, the following:

Parts 1-amino-4-anilinoanthraquinone 2 sulphonic arid V2 v p-Nitroaniline N ethyl N sulphatoethylaniline 2 Citronine Y- (Colour Index No. 146) 1 /4 The assistant of Example 1 2.6 50 parts dry weight of oil-dressed molesklns areintroduced into the above dyebath at 45 C. After minutes there are added 2 parts of acetic acid. Dyeing is continued for 20 minutes longer. The moleskins are then removed, thor- I oughly rinsed in water at 30-35 C., drained and dried at a temperature not exceeding C.

There is thus obtained a clear level-dyed brown shade.

I claim:

A dyebath which contains Lissamine Green-V (Colour Index No. 735) and, for improved levelness is dyeing the softer furs, an assistant, the

ratioof said dye to said assistant being about 1 parts of said dye to 2.23 parts of the assistant, said assistant consisting essentially of about 5% p to about 25% of cetyl pyridinium bromide and 1 the remainder essentially polyglycerol ricinoleate. 30

Join: 'BURCHILL.

' Patent No. 2,556,221.

CERTIFICATE OF commcnou. I, a v

i r], 19h;- JOHN .BURCHILL.

It is hereby certified that error aiapeare in the printed specification of the afpove zmmbered' patent; requiring Correction as fo1lbws:- Page 2, sec- 'end columh; line 21;, claim 1, for Piaf read --in--; and that the said Letjers Patentl should be read with this. cerreotion therein that the same may pnfom to the record of the case in the Patent Office.

Sigx mdend sealed "this 8th day or many, A. 1). 191m.

. flem y Ven Ar sdale, (igfeal) j Acting-commissioher of Patents.. 

